An app distributed via Google Play may not modify, replace, or update itself using any method other than Google Play’s update mechanism. Likewise, an app may not download executable code (e.g. dex, JAR, .so files) from a source other than Google Play. This restriction does not apply to code that runs in a virtual machine and has limited access to Android APIs (such as JavaScript in a webview or browser).

The plan for Kodi v18 moves even more 'core' functionality to downloaded binary addons. The entire virtual file system, for example. This means that say for SMB server access, a binary addon would need to be loaded from the kodi repo (or others) and installed. This action is explicitly forbidden under GooglePlay.

Can't say I did not warn them long ago App Stores such as GooglePlay are tightening up restrictions as they realize that some people are just thieves and the honor system just does not work in the real world.

Just another example of why we at MrMC stripped out the addon feature.